From: Randy Dunlap <rdunlap@infradead.org>
To: Hinko Kocevar <hinko.kocevar@ess.eu>,
Linux PCI <linux-pci@vger.kernel.org>
Subject: Re: /proc/iomem and /proc/ioports show 0 for address range
Date: Wed, 13 Jan 2021 10:45:07 -0800 [thread overview]
Message-ID: <ae1da3a0-11d3-b1dd-601c-3169e783fcb4@infradead.org> (raw)
In-Reply-To: <375ef4e6-b9a1-d4f2-81b6-582f2152820d@ess.eu>
On 1/13/21 2:29 AM, Hinko Kocevar wrote:
> [I noticed this while working on PCI devices; not sure which kernel list would be best for this, though]
>
> I noticed that my system shows address range for iomem and ioports as all 0. Sometimes (after a power cycle) the addresses are proper, albeit I have not been able to see that in a while now, after performing numerous reboots in the last coupe of days.
>
> FWIW, I think the list of devices (names, count) looks the same in both cases. The system seems to work in both cases; at least I have not seen any complaints in kernel logs, OTOH, not sure what the error message would be.
>
> What may be the reason for not getting the proper addresses listed?
config STRICT_DEVMEM
bool "Filter access to /dev/mem"
and
config IO_STRICT_DEVMEM
bool "Filter I/O access to /dev/mem"
so what are your CONFIG_STRICT_DEVMEM and CONFIG_IO_STRICT_DEVMEM set to?
What do you see in /proc/iomem and /proc/ioports if you are admin/root?
That should be non-zero values.
> This likely poses any issues for userspace tools that would look at those /proc files, OTOH, I wonder if would kernel suffer in any way as well?
Yes, it could affect userspace.
> Kernel version is 5.10.0 (pci git tree).
>
> [dev@bd-cpu18 ~]$ cat /proc/iomem
> 00000000-00000000 : Reserved
> 00000000-00000000 : System RAM
> 00000000-00000000 : Reserved
> 00000000-00000000 : PCI Bus 0000:00
> 00000000-00000000 : Video ROM
> 00000000-00000000 : Reserved
> 00000000-00000000 : System ROM
> 00000000-00000000 : System RAM
> 00000000-00000000 : Kernel code
> 00000000-00000000 : Kernel rodata
> 00000000-00000000 : Kernel data
> 00000000-00000000 : Kernel bss
--
~Randy
You can't do anything without having to do something else first.
-- Belefant's Law
next prev parent reply other threads:[~2021-01-13 18:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 10:29 /proc/iomem and /proc/ioports show 0 for address range Hinko Kocevar
2021-01-13 18:45 ` Randy Dunlap [this message]
2021-01-13 21:27 ` Hinko Kocevar
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